It really depends on several factors including whether you want a comedy or a serious piece, how much cutting you are willing to do, if you are doing a duo or a solo, and what kind of message you want to send with your performance.

My most favorite duo piece I have seen is "Fight Club". I use this one as an example for my Oral Interpretation class at school. I have also seen cuttings from "The Chalk Garden", and "The Odd Couple" that have worked well.